On December 21, 1984, Captain Imran Usman and First Officer Mahmood Ahmed operated an F-27 aircraft (Registration AP-AUR) on scheduled flight PK-652 from Lahore to Islamabad. During the flight, while at F.L. 100, the crew identified a technical abnormality regarding the pneumatic system. The sequence of events and subsequent landing included: System Over-Pressure: The emergency bottle pneumatic pressure was observed at approximately 3500 P.S.I., which exceeded the caution yellow mark and approached the red over-pressure limit. In-Flight Correction: To vent the excessive pressure, the Captain utilized the emergency brakes until the pressure was reduced to a safer level of 2800 P.S.I.. Precautionary Measures: The emergency brake knob was returned to the "OFF" position, and both pilots operated the brake paddles to ensure no residual pressure remained trapped in the system. Landing and Roll-out: The aircraft performed a normal approach and touchdown on Runway 30 at Islamabad Airport. Directional Control Difficulty: After selecting ground fine pitch, the aircraft began to swing toward the left. The Captain attempted to counteract the movement with full rudder and nose wheel deflection, but initially reported receiving little response from the aircraft.
